Many people suffer from vision impairments. A person is said to be “near-sighted” when objects within a certain range appear very clearly, while distant object appear blurry at all times. A person is said to be “far-sighted” when close objects appear out of focus, while distant object appear to be in focus.
Nearsightedness is the result of a condition call myopia, which occurs when light entering the eye focuses in front of the retina instead of directly on it. Myopia is caused by a cornea that is steeper is shape, or an eye that is longer in depth when compared to an eye with normal 20/20 vision. Nearsighted people typically see well up close, but have difficulty seeing far away.
Myopia is often discovered in school-age children who report having trouble seeing the chalkboard. Near-sightedness usually becomes progressively worse through adolescence and stabilizes in early adulthood. Myopia is a condition that is typically inherited, and is often corrected with Vision can with glasses, contact lenses, or surgical procedures once the persons vision has stabilized in adulthood.
Farsightedness is a result of a condition called hyperopia, which occurs when light entering the eye is focused behind the retina instead of directly on the retina. Hyperopia is caused by a cornea that is flatter in shape, or an eye that is shorter in depth when compared to an eye with normal 20/20 vision. While most farsighted people usually have trouble seeing up close, farsighted people may also have difficulty seeing far away as well.
Young people with mild to moderate hyperopia are often able to see clearly because their natural lens can adjust, or accommodate to increase the eye's focusing ability. However, the eye gradually loses the ability to accommodate at around the age of 40 years old, and the blurred vision from hyperopia becomes much more apparent. Young patients may or may not require glasses or contact lenses to correct for hyperopia depending on their ability to compensate for their farsightedness with accommodation. Glasses or contact lenses are typically required for older patients.
Although many vision problems can be corrected with contact lenses, there are some exceptions. Some of the conditions that might keep a person from wearing contact lenses are: frequent eye infections, severe allergies, dry eye (improper tear film), a work environment that is very dusty or dirty and inability to handle and care for the lenses properly. Also, some vision impairments simply cannot be corrected by contact lenses.
There are some reading lenses and magnifying glasses that are available to assist people in reading books, documents and the like without the use of reading glasses. These are particularly useful when the person encounters small print during an activity which makes it inconvenient or difficult to stop and put on reading glasses.
One example reading lens device is a book mark such as that shown in U.S. Pat. No. 3,140,883 issued to R. L. Anthony on Jul. 14, 1964. The illustrated book mark can be integrally attached to a book such as a telephone directory or a dictionary, where the end of the book mark includes a sealed pocket that holds a plastic magnifying lens.
A pocket sized magnifying device is shown in U.S. Pat. No. 3,409,347 issued to R. Vogel on Nov. 5, 1968. The illustrated pocket sized magnifying device includes a pocket pouch adapted to be carried in the breast or hip pocket of the user or in a purse or wallet. The lens in the device is formed of a transparent plastic sheet that has a lens molded into its upper surface. The lens is slidably retracted into and extended out of the pocket.
A credit card with a magnifying lens is shown in U.S. Pat. No. 5,608,203 to Finkelstein et al. on Mar. 4, 1997. The illustrated device is a credit card that includes a rigid base with a transparent area. Fresnel contours are formed on an upper surface of the transparent area, which is illustrated as a horizontal window in the central region of the credit card. The transparent area and the Fresnel contours are joined to form a magnifying lens for the credit card device.